Agricultural machines include both combine and forage harvesters. The combine harvester, or simply combine, is a machine that harvests, threshes, and cleans grain plants. The forage harvester harvests forage plants to make silage. Some combines utilize shakers to separate the grain from the chaff and straw-walkers to eject the straw while retaining the grain. Over time, harvesters have enlarged including larger manufactured components, such as headers and tires. Larger harvesters cut larger areas of crops and/or store more grain.
Today's combines and forage harvesters are equipped with removable heads, or headers, designed for particular crops. The header is mounted to the front of the harvester for harvest. The header can be removed from the harvester, so that the harvester may be driven on roads, wherein the harvester without the header may form a narrower configuration to fit within the width of the road or a lane in the road. When a header is attached to the front of a combine, the weight of the header applies a moment acting about the harvester's front axle. This moment acts to lessen the amount of harvester weight carried by the rear axle. In many harvesters the rear wheels and rear axle serve to steer the harvester. When the header is mounted to the front of the harvester, it is necessary to have a sufficient amount of the harvester weight applied on the rear axle so that the harvester remains stable for directional control, for rear wheel traction if the harvester has a power guide axle, and to prevent the harvester from tipping forward causing the header to contact the ground and introduce undesirable impact or damage to the header and/or harvester. Often it is necessary to counteract the moment caused by header weight by adding weight to the rear of the harvester, which may include suitcase weights added on the rear axle, weights added directly to the rear wheels, or fluid (e.g. calcium chloride) introduced into the rear or steer tires.
The addition of various types of weights at the rear of the harvester results in a heavier harvester. A heavier harvester introduces undesirable results including: increased soil compaction; an inability to harvest during muddy conditions; and necessity to design stronger and thus often more costly harvester components to absorb the increased loads. As harvesters get larger and heavier, more weight must be added to the rear of the harvester to offset load. Often the weight added to the rear needs to be variable, because some harvester operators drive with larger header attachments than other operators using the same harvester model.
When the header is removed, much of the added weight is transferred to the rear axle. When the weight on the rear axle becomes excessive, the rear axle and associated support structure become susceptible to failure. Load bearing on the rear axle is becoming more of a concern with larger harvesters and the additional weight added to the rear wheels. However, a harvester may only operate without a header for a short period of time, so redesigning the components in or around the steering rear wheels for load absorption is cost inefficient.
What is needed is a device for an agricultural machine, or harvester, that may be configured to remove weight and offset loading on the rear axle when the header is either replaced with a lighter header or removed entirely from the front of the machine. This would minimize the possibility of structural failure and/or damage to the machine.